QHY9 offset and gain setting?

[stoffe]

Hello

I got a QHY9 camera and I do not really know how to configure these two settings. It looks like this now. I guess my gain is to low? What setting should I choose?

 

 

[Oddsocks]

This document explains the steps to take, bit lengthy but easy to follow:

http://www.astropixel.gr/uploads/7/8/3/5/7835053/scientifically_determining_ccd_gain_and_offset.pdf

Also a Craig Stark blog which is a general description of the offset and gain functions:

http://www.stark-labs.com/help/blog/files/GainAndOffset.php

William.

[stoffe]

Thanks! I guess I can not copy the settings from a another QHY9 owner directly then.

 

[Oddsocks]

41 minutes ago, stoffe said:

I guess I can not copy the settings from a another QHY9 owner directly then.

 

You can copy from someone else but the offset and gain values they use will only apply to your camera if the factory QA was observed exactly for each camera assembled and that there has been no calibration drift caused by ageing components in your camera since it left the factory.

[stoffe]

Thanks, I guess I need to understand those links and do it a try then.

[stoffe]

Is it possible that gain should be at that low value that I have in my settings?

[Oddsocks]

1 hour ago, stoffe said:

Is it possible that gain should be at that low value that I have in my settings?

Yes, that value is quite plausible.

In the first document I linked to: ( http://www.astropixel.gr/uploads/7/8/3/5/7835053/scientifically_determining_ccd_gain_and_offset.pdf ) the authors tested their QHY9M and determined their gain as 17% with an offset of 112 so your current settings of 19% and 110 are not that far away but remember these numbers though very small have a big effect on the way the camera records the image and to get the best out of the camera you need to measure and set the gain and offset accurately.

[tooth_dr]

@Xiga

[Xiga]

On 29/04/2020 at 21:47, tooth_dr said:

@Xiga

Thanks Adam. 

It appears to be a dead link though. It looks like the pdf no longer exists.

I have found a good article by Craig Stark here:  http://www.stark-labs.com/help/blog/files/GainAndOffset.php  and also a good thread (comment #7) over on iceinspace here:  http://www.iceinspace.com.au/forum/showthread.php?t=149431  so i'm going to give this a go and see how i get on. 

Couple of quick questions for you if you don't mind:

1. Being older tech, i presume i will need to warm up the camera before bringing it back inside? I've read that with modern cooled CMOS cameras it's apparently not needed to gradually cool or warm them, you can supposedly do either safely in just a few mins, but with the Qhy9 should i cool and warm over a longer period, like 10 mins? 

2. You had mentioned that the back focus was 17.3mm. I've found two sources online that give 2 different figures, this one has a schematic that shows 17.3mm https://www.highpointscientific.com/qhy-qhy9-classic-8-3-mp-cooled-monochrome-ccd-imaging-camera-qhy9m   but then i found a link to a manual that says it is 15mm  here  https://www.qhyccd.com/file/repository/PDF/QHY9 CCD camera user guide.pdf   Are there 2 different models of this camera out there, and was it the previous owner that confirmed it is definitely 17.3mm? 

[tooth_dr]

@xiga apologies I never checked that link before tagging you.

1). I always warm and cool over 10 minutes, and probably would leave it in a cooler part of the house after that.  I warm mine to ambient which could be 5 degrees, then leave it at that temp in the obs.

2). Yes I was going by the mechanical drawing rather than the text.  It could be that I'm out 2.3mm but my stars look ok at the edge of the field.  You could try both. 

 

It's actually clear, so that's a bonus!

[tooth_dr]

Actually just found this diagram, 15.55mm.  I think this is right because the newer QHY9 has screw holes on the side, mine doesn't, and this image shows it with no screw holes.  The images with 17.3mm have screw holes for the leads

http://www.y-tomita.co.jp/ccd/qhyccd/qhy9.html